Why doesn't my mac startup after a failed zero writing?

I'm on a macbook pro, os x 10.6 snow tiger. I had only 10GB of free space on my disk, and I decided to write zeros over it. By accident I interrupted the writing and the free space became a temporary 10GB file, which left me with a full disk. I found the file and moved it to the thrash but got an error message when trying to securely erase it. I verified the disk with disk utility and got a message telling me to restart the system with the installation disc on it. I did, and since then I cannot boot my mac again: it makes the startup chime, goes to the gray screen with the "clock" ticking under it, but stays there forever.

So far, in no exact order:

-Tried solo mode and fsck -fy until i got the "The Volume Machintosh HD appears to be OK";

-Tried booting with option pressed, and then tried both the installation disc and the hard disk... both got the mac screen frozen once I clicked at them;

-Tried putting the install disc on a pc and through ethernet to acces the disc on mac;-Tried leaving the macbook boots for 10 minutes...

-Executed a hardware test;

-Tried booting on safe mode.

Nothing worked and I have no idea how to repair the disk. I wonder if there's a way to delete the corrupted temporary file or any other way to make it work. Any help would be highly appreciated. Thanks in advance.

ps: I found a website in which they charge for remote advicing, I would even pay for a solution, as long as it really works.Anyone had any success with such online services?

When you Zero Erased the free space, it did create a temp file to read back so it can confirm that zero's were written, in fact it's hack of mine to pre-map off failing sectors before placing real data on the drive.

You tried the Safe mode trick, which you hold the Shift Key down while booting, this doesn't seen to work for you, so you'll need to create a bootable external drive, whcih you then can access the internal drive to remove files. (movies is a prime target)

Tried putting the install disc on a pc and through ethernet to acces the disc on mac;

Since you have a PC, you can download and burn a ISO of Parted Magic to a cd.

Connect a external drive, reboot the Mac holding the c key (or option key) down, you then boot off the Parted Magic cd and choose the default "install in RAM" the disk will auto-eject so watch out for it.

I'm on a macbook pro, os x 10.6 snow tiger. I had only 10GB of free space on my disk, and I decided to write zeros over it. By accident I interrupted the writing and the free space became a temporary 10GB file, which left me with a full disk.

How exactly did you interrupt the process? The erase free space option does not normally create any temporary files (except possibly journaled entries) so what probably happened was the file system was left in a corrupted state if you forced a shutdown.

Using fsck -fy apparently repaired the damage, but the repair may have deleted corrupted OS files on it necessary to start up the Mac.

-Tried booting with option pressed, and then tried both the installation disc and the hard disk... both got the mac screen frozen once I clicked at them;

The Startup Manager (option key startup) is completely independent of anything on the hard drive. If you used a suitable installation DVD & chose it, the Mac should have started up from it no matter what state the internal drive was in. If not, it means that you weren't using a DVD with a compatible version of Snow Leopard on it, that you didn't select the DVD, or that something else is wrong with your Mac.

One thing you can try is resetting PRAM, which sometimes helps in situations like this. Then try restarting from the DVD again, after making sure it is either the original system disk that came with the Mac or has a version of the OS at least as new as the original version that came with that Mac.

-Tried booting with option pressed, and then tried both the installation disc and the hard disk... both got the mac screen frozen once I clicked at them;

It does appear you might have used the wrong OS X install disk to try to boot from.

10.4 Tiger

10.5 Leopard

10.6 Snow Leopard

10.6.3 Snow Leopard retail disk is a full OS X install disk, not just a upgrade disk it apparantly seems to be when you stick it in and run the upgrade installer.

Clean and polish the bottom of the 10.6 disk with a soft cloth and a bit of rubbing alcohol to clean the oils and polish to a shine, stick it into the machine and reboot holding the option key or c key down to boot from it.

If you can't, then my guess is the disk is bad, as the computer should be able to boot from the disk.

Do the PRAM Reset as R mentioned, as some settings are stored there and need to be cleared out as you can't create a data recovery disk without a working 10.6 disk.

If you need a new 10.6 disk, if your machine was upgraded from 10.5/10.4 then you can order the 10.6.3 Snow Leopard $29 retail disk on line at Apple.com. If your installer disk says 10.6.3+ then you need to call Apple for machine specific version disks.

If you have the disk stuck in the machine, reboot holding the trackpad button down, or the option key for Startup Manager, select the disk and hit the eject key on the keyboard.

OK, I stand corrected about that. However, there is no indication that they are ever read back to verify the zero write. At the end of the process, the files are simply deleted, & that happens far to quickly in every test I've made for even a fraction of the temp file(s) to be read.

The main temp file (named "EFTFile1.sparseimage" on my systems) gradually builds in size & seems to function only as placeholder to prevent new files being written to the free space being overwritten with zeros. (You can verify this by trying to copy a file larger than the remaining free space to the drive as the temp file grows in size -- you get a 'not enough space' error until the process completes.)

If you stop the process before it is complete, the file is only as large as the amount of free space already zeroed, not the entire free space on the drive. If you stop it with the Skip button, the files are deleted immediately. I'm not sure what would happen if you force quit Disk Utility or forced a shutdown of the Mac, but some incomplete testing suggests that if this is the boot drive the temporary files are deleted automatically as part of the boot process on the next startup.

Regardless of all that, the OP still should be able to start up from the system DVD that came with the Mac since it doesn't reference the HD for anything -- in fact, you can normally start up from the system DVD even if the drive is dead, unformatted, or even removed.

To clarify slightly what ds store meant about the wrong disk, if your Mac came with Snow Leopard installed, it may require a later version of that OS than is available on the Snow Leopard retail disks to start up.

If you are unsure about this, refer to http://support.apple.com/kb/HT1159 & check the version(s) of the OS that it could have come with. If the version is later than 10.6.3 you can't start it up using the retail Snow Leopard installer DVD because it lacks support for the newer hardware on your Mac.

Some things to look at. The first copied I believe from MacGeekery, which is perhaps no longer available. I can't get it.

Sometimes, when using the erase free space function of Disk Utility, the process will be interrupted by a crash, hang, power outage, or small mammal urinating on the power supply. Should this happen, you’ll find that your disk has suddenly lost the majority of its free space and nothing you do in the GUI will show you where it is. No amount of checking the disk will bring it back, because it’s not a catalog problem.

Disk Utility accomplishes the erase feature by creating large sparse image files in a preset directory. It then deletes them with the srm tool (secure remove) and an overwrite pattern of your choice. If Disk Utility is interrupted, this sparse image is left on the disk just taking up space. Starting another free space erase session makes another file, instead of cleaning up the previous one. So, as there are no checks in Disk Utility for cleaning up this failed process, so you have to hunt it down manually.

There are a variety of ways of doing this, but I’ll cut to the chase and give you the answer. The files are created in /var/root/Library/Caches/TemporaryItems and are sequential variations of the name EFTFile1.sparseimage. Simply remove these files (as root) to reclaim your free space and then start the process again to finish the task.

Be extremely careful with the above command. Copy/Paste it in only. One typo/wrong space and you may erase your entire drive. If this path is no longer present in Snow Leopard, you may get a message "command not found," or "no such file or directory." You may also get "permission denied."

At least in theory, the contents of /var/root/Library/Caches/TemporaryItems should be deleted on a normal shutdown & restart. (This of course only applies to the startup volume.) That seems to be what happened at least for one of the posters to https://discussions.apple.com/message/10704330#10704330. The same thing should happen to the temp file(s) if one uses the "Skip" button, at least if you give it a few seconds to tidy up before quitting Disk Utility or using any method to force quit it or force a shutdown of the Mac.

Thus, I still think it is important to know exactly how our OP interrupted the secure erase & more importantly, why the Mac won't boot from the install DVD. Without another Mac to use target Disk Mode to access the internal HD or an extra HD already capable of booting the Mac, there is no way to use OmniDisk Sweeper or any other third party utility to find or remove the file(s) using up the remaining space on the internal. And if the OS has been damaged, it will still have to be reinstalled to set things right.

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